package CN.EDU.SEU.程序员代码面试指南.chapter_8_arrayandmatrix;

import java.util.Arrays;

public class Problem_20_PrintMaxTopK {

    public static void printTopK(int[][] matrix, int topK) {
        int heapSize = matrix.length;
        HeapNode[] heap = new HeapNode[heapSize];
        for (int i = 0; i != heapSize; i++) {
            int index = matrix[i].length - 1;
            heap[i] = new HeapNode(matrix[i][index], i, index);
            heapInsert(heap, i);
        }
        System.out.println("TOP " + topK + " : ");
        for (int i = 0; i != topK; i++) {
            if (heapSize == 0) {
                break;
            }
            System.out.print(heap[0].value + " ");
            if (heap[0].index != 0) {
                heap[0].value = matrix[heap[0].arrNum][--heap[0].index];
            } else {
                swap(heap, 0, --heapSize);
            }
            heapify(heap, 0, heapSize);
        }
    }

    public static void heapInsert(HeapNode[] heap, int index) {
        while (index != 0) {
            int parent = (index - 1) / 2;
            if (heap[parent].value < heap[index].value) {
                swap(heap, parent, index);
                index = parent;
            } else {
                break;
            }
        }
    }

    public static void heapify(HeapNode[] heap, int index, int heapSize) {
        int left = index * 2 + 1;
        int right = index * 2 + 2;
        int largest = index;
        while (left < heapSize) {
            if (heap[left].value > heap[index].value) {
                largest = left;
            }
            if (right < heapSize && heap[right].value > heap[largest].value) {
                largest = right;
            }
            if (largest != index) {
                swap(heap, largest, index);
            } else {
                break;
            }
            index = largest;
            left = index * 2 + 1;
            right = index * 2 + 2;
        }
    }

    public static void swap(HeapNode[] heap, int index1, int index2) {
        HeapNode tmp = heap[index1];
        heap[index1] = heap[index2];
        heap[index2] = tmp;
    }

    public static int[][] generateRandomMatrix(int maxRow, int maxCol,
                                               int maxValue) {
        if (maxRow < 0 || maxCol < 0) {
            return null;
        }
        int[][] matrix = new int[(int) (Math.random() * maxRow) + 1][];
        for (int i = 0; i != matrix.length; i++) {
            matrix[i] = new int[(int) (Math.random() * maxCol) + 1];
            for (int j = 0; j != matrix[i].length; j++) {
                matrix[i][j] = (int) (Math.random() * maxValue);
            }
            Arrays.sort(matrix[i]);
        }
        return matrix;
    }

    public static void printMatrix(int[][] matrix) {
        for (int i = 0; i != matrix.length; i++) {
            for (int j = 0; j != matrix[i].length; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        int[][] matrix = generateRandomMatrix(5, 10, 1000);
        printMatrix(matrix);
        System.out.println("===========================");
        printTopK(matrix, 100);
    }

    public static class HeapNode {
        public int value; // ֵ��ʲô
        public int arrNum; // �����ĸ�����
        public int index; // ����������ĸ�λ��

        public HeapNode(int value, int arrNum, int index) {
            this.value = value;
            this.arrNum = arrNum;
            this.index = index;
        }
    }

}
